Introduction to Anatomy Study Notes

Definition of Anatomy

  • Anatomy is the science that studies:
    A. Body structures and their relationships.
    B. Levels of structural organization.

Levels of Structural Organization in the Body

  • Six levels from smallest to largest:
    1. Chemical level
    2. Cellular level
    3. Tissue level
    4. Organ level
    5. System level
    6. Organismal level
1. Chemical Level
  • Includes atoms (smallest units of matter) and molecules (two or more atoms joined).
  • Atoms: Carbon (C)(C), Hydrogen (H)(H), Oxygen (O)(O), Nitrogen (N)(N), Phosphorus (P)(P), Calcium (Ca)(Ca), Sulfur (S)(S).
  • Molecules (Examples): Deoxyribonucleic acid (DNA), Glucose.
2. Cellular Level
  • Cells are the basic structural and functional units of an organism, formed by molecules.
3. Tissue Level
  • Tissues are groups of cells and surrounding materials working together for a specific function.
  • Four types: Epithelial, Connective, Muscular, Nervous.
4. Organ Level
  • Organs are composed of two or more tissue types, performing specific functions with recognizable shapes.
  • Examples: Stomach, Skin, Heart.
5. System Level
  • A system consists of related organs.
  • Example: Digestive system (mouth, stomach, intestines) breaks down and absorbs food.
6. Organismal Level
  • An organism is a living individual; all body parts function together.

Cellular Level of Organization

  • The human body has about 200 different cell types.
Parts of a Cell
  1. Plasma Membrane: Outer surface, separating internal/external environments.
  2. Cytoplasm: Cellular contents between the plasma membrane and nucleus.
    A. Cytosol: Fluid portion (water, solutes, particles).
    B. Organelles: Specialized structures with specific functions (e.g., cytoskeleton, ribosomes, ER, Golgi, lysosomes).
  3. Nucleus: Large organelle housing most cellular DNA.

Structure of the Plasma Membrane

  • Basic framework: lipid bilayer.
  • Components: Phospholipids (approx. 75%), Cholesterol, Glycolipids.
Arrangement of Membrane Proteins
  • 1. Integral Proteins: Extend into or through the lipid bilayer; most are transmembrane.
  • 2. Peripheral Proteins: Attached to membrane surfaces (not embedded).

Functions of Integral Proteins

  1. Ion channels: Allow specific ions (e.g., K+K+) to pass.
  2. Carriers: Selectively move polar substances/ions.
  3. Receptors: Cellular recognition sites (e.g., insulin receptors bind insulin).
  4. Enzymes: Catalyze specific chemical reactions.
  5. Linkers: Anchor proteins to neighboring cells and cytoskeletal elements.
Cytoskeleton
  • Network of protein filaments providing cell structure and shape.
  • Three types:
    1. Microfilaments: Thinnest, made of actin and myosin.
    2. Intermediate filaments: Provide mechanical support.
    3. Microtubules: Largest, hollow tubes (tubulin); determine cell shape and aid organelle movement.
Organelles
  • Specialized structures within the cell:
    1. Centrosome: Pair of centrioles and pericentriolar material.
    2. Ribosomes: Sites for protein synthesis (free ribosomes make cytosolic proteins; associated ribosomes make membrane/secreted proteins).
    3. Endoplasmic Reticulum (ER):
    • Rough ER: Studded with ribosomes; synthesizes glycoproteins/phospholipids, detoxifies.
    • Smooth ER: Lacks ribosomes; synthesizes fatty acids and steroids (e.g., estrogens).
    1. Golgi Complex: Modifies, sorts, packages, and transports proteins from Rough ER; forms secretory vesicles.
    2. Lysosomes: Contain digestive enzymes; digest cellular substances, worn-out organelles, and perform autolysis.
    3. Nucleus: Houses most DNA (genes), controls cell structure/activities.
    • Chromosomes: 46 in somatic cells (human), DNA coiled with proteins (chromatin).
    • Chromatin: DNA wrapped around histones (nucleosomes) aids DNA organization during replication, forming chromatids and chromosomes.